| Message ID | 20190911132839.23336-3-richard.weiyang@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | migration/qemu-file: cleanup and refine qemu-file | expand |
* Wei Yang (richard.weiyang@gmail.com) wrote: > From: Wei Yang <richardw.yang@linux.intel.com> > > In add_to_iovec(), qemu_fflush() will be called if iovec is full. If > this happens, buf_index is reset. Currently, this is not checked and > buf_index would always been adjust with buf size. > > This is not harmful, but will waste some space in file buffer. > > This patch make add_to_iovec() return 1 when it has flushed the file. > Then the caller could check the return value to see whether it is > necessary to adjust the buf_index any more. > > Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > --- > v2: > * wrap these common steps into add_buf_to_iovec() > --- > migration/qemu-file.c | 43 ++++++++++++++++++++++++++----------------- > 1 file changed, 26 insertions(+), 17 deletions(-) > > diff --git a/migration/qemu-file.c b/migration/qemu-file.c > index 47f16d0e54..417eeba64b 100644 > --- a/migration/qemu-file.c > +++ b/migration/qemu-file.c > @@ -382,8 +382,16 @@ int qemu_fclose(QEMUFile *f) > return ret; > } > > -static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, > - bool may_free) > +/* > + * Add buf to iovec. Do flush if iovec is full. > + * > + * Return values: > + * 1 iovec is full and flushed > + * 0 iovec is not flushed > + * > + */ > +static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, > + bool may_free) > { > /* check for adjacent buffer and coalesce them */ > if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base + > @@ -401,6 +409,19 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, > > if (f->iovcnt >= MAX_IOV_SIZE) { > qemu_fflush(f); > + return 1; > + } > + > + return 0; > +} > + > +static void add_buf_to_iovec(QEMUFile *f, size_t len) > +{ > + if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) { > + f->buf_index += len; > + if (f->buf_index == IO_BUF_SIZE) { > + qemu_fflush(f); > + } Yep, that's better. Dave > } > } > > @@ -430,11 +451,7 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size) > } > memcpy(f->buf + f->buf_index, buf, l); > f->bytes_xfer += l; > - add_to_iovec(f, f->buf + f->buf_index, l, false); > - f->buf_index += l; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > - } > + add_buf_to_iovec(f, l); > if (qemu_file_get_error(f)) { > break; > } > @@ -451,11 +468,7 @@ void qemu_put_byte(QEMUFile *f, int v) > > f->buf[f->buf_index] = v; > f->bytes_xfer++; > - add_to_iovec(f, f->buf + f->buf_index, 1, false); > - f->buf_index++; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > - } > + add_buf_to_iovec(f, 1); > } > > void qemu_file_skip(QEMUFile *f, int size) > @@ -761,11 +774,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream, > } > > qemu_put_be32(f, blen); > - add_to_iovec(f, f->buf + f->buf_index, blen, false); > - f->buf_index += blen; > - if (f->buf_index == IO_BUF_SIZE) { > - qemu_fflush(f); > - } > + add_buf_to_iovec(f, blen); > return blen + sizeof(int32_t); > } > > -- > 2.15.1 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
diff --git a/migration/qemu-file.c b/migration/qemu-file.c index 47f16d0e54..417eeba64b 100644 --- a/migration/qemu-file.c +++ b/migration/qemu-file.c @@ -382,8 +382,16 @@ int qemu_fclose(QEMUFile *f) return ret; } -static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, - bool may_free) +/* + * Add buf to iovec. Do flush if iovec is full. + * + * Return values: + * 1 iovec is full and flushed + * 0 iovec is not flushed + * + */ +static int add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, + bool may_free) { /* check for adjacent buffer and coalesce them */ if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base + @@ -401,6 +409,19 @@ static void add_to_iovec(QEMUFile *f, const uint8_t *buf, size_t size, if (f->iovcnt >= MAX_IOV_SIZE) { qemu_fflush(f); + return 1; + } + + return 0; +} + +static void add_buf_to_iovec(QEMUFile *f, size_t len) +{ + if (!add_to_iovec(f, f->buf + f->buf_index, len, false)) { + f->buf_index += len; + if (f->buf_index == IO_BUF_SIZE) { + qemu_fflush(f); + } } } @@ -430,11 +451,7 @@ void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, size_t size) } memcpy(f->buf + f->buf_index, buf, l); f->bytes_xfer += l; - add_to_iovec(f, f->buf + f->buf_index, l, false); - f->buf_index += l; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, l); if (qemu_file_get_error(f)) { break; } @@ -451,11 +468,7 @@ void qemu_put_byte(QEMUFile *f, int v) f->buf[f->buf_index] = v; f->bytes_xfer++; - add_to_iovec(f, f->buf + f->buf_index, 1, false); - f->buf_index++; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, 1); } void qemu_file_skip(QEMUFile *f, int size) @@ -761,11 +774,7 @@ ssize_t qemu_put_compression_data(QEMUFile *f, z_stream *stream, } qemu_put_be32(f, blen); - add_to_iovec(f, f->buf + f->buf_index, blen, false); - f->buf_index += blen; - if (f->buf_index == IO_BUF_SIZE) { - qemu_fflush(f); - } + add_buf_to_iovec(f, blen); return blen + sizeof(int32_t); }